WhenCalled failed on MethodBase fake

public void CompileTimeValidate_MethodIsAbstract_ReturnFalse() {
         var fakeMethod = Isolate.Fake.Instance<MethodBase>();
         Isolate.WhenCalled(() => fakeMethod.DeclaringType).WillReturn(typeof(ChargerBase));
         Isolate.WhenCalled(() => fakeMethod.IsAbstract).WillReturn(true);
         var aspect = new RaiseEventWhenChargerActionFailsAttribute();

         var result = aspect.CompileTimeValidate(fakeMethod);

         Assert.IsFalse(result);
      }